Background: Bone marrow is a frequent site of metastatic tumors, especially from breast, lung, and prostate cancers. Metastatic tumor in the bone marrow may influence the response to treatment, overall survival, and resulting decreased hematopoiesis. Diffusely and homogenously bone marrow uptake in 18F-FDG PET/CT scan is frequently observed which can caused by many conditions. Material and methods: We retrospectively analyzed the consecutive records of F-18 FDG PET scans performed from April 2011 to August 2013 at Mochtar Riady Comprehensive Cancer Center Siloam Hospital, A total of 2952 result were reviewed. 16 patients with diffusely and homogenously bone marrow uptake in F-18 FDG PET/CT whole body scan between January 2012 and December 2013 were evaluated to find out the etiology. Results: From 2952 patients performed 18F-FDG-PET/CT there are 16 patients (5 men, 11 women) with diffusely and homogenously increased FDG uptake in bone marrow, mean age: 52 years, range 5–82 years. It was found that 6 of 16 FDG PET/ CT positive patient with solid tumors and 10 of 16 FDG PET/CT with non solid tumors. Malignancy was observed in 14 patients and benign in 2 patients. Diffusely and homogenously uptake due to 1 patiets with Idiopathic thrombocytopenic purpura (ITP) , 6 patient with anaemia, 7 patients with chemotherapy, 1 patients with Granulocyte Colony-Stimulating Factor (G-CSF) and 1 patients with extra-nodal non-hodgkin lymphoma were observed. Conclusion: Diffusely and homogenously increase bone marrow on 18F FDG PET/ CT whole body scan uptake can be seen in malignant or benign disease and history of treatment. Spleen uptake are observed at the initial imaging than bone marrow involvement while spleen uptake more frequently reflects disease involvement.